1. Field of the Invention
This invention relates to an ophthalmologic instrument interchangeably provided with various cameras.
2. Related Background Art
A prior-art ophthalmologic instrument, for example, an eye fundus camera, is comprised of a body of the instrument including a power source, and a removable camera section. In some cases, a power source section is provided discretely from the body. There are a plurality of kinds of camera instruments such as one having a 35 mm camera, one having an instant camera, and one having a television camera, and they are interchangeable.
As the removable camera section of an ophthalmologic instrument, there is a 35 mm camera, an instant camera or the like. These cameras each have an electrical contact on a camera mount, and may be directly electrically connected by the camera mount, or only an electrical signal may be taken out by a cable and the camera may be connected by a discretely provided connector instead of the camera mount.
The kinds of signals differ depending on a camera section connected. The same signals can share an electrical contact between a plurality of camera sections, but in the case of signals incompatible with each other, it is necessary to provide a contact discretely. This has led to the problem that the number of the contacts of the camera mount is increased. There has also been the problem that there is a limit in the number of contacts provided on the camera mount and a greater number of contacts results in a smaller size of the contacts and a higher possibility of unsatisfactory contact occurring.
As a countermeasure for decreasing the number of the contacts of the camera mount to eliminate such problems, there has been adopted a method of changing a terminal for reading out the state of the camera section from binary one representing the ON/OFF of a switch to one in which for example, a change occurs stepwise from 0 V to 5 V, thereby reducing the number of terminals to one. For example, the conditions regarding film, such as film unloaded condition, film loaded condition and film end, have been divided into several voltage levels, whereby the information of the camera section side has been transmitted to a power source section or a body.
Here, an eye fundus camera will be described somewhat in detail.
In an ophthalmologic instrument such as an eye fundus camera or a slit lamp, observation or photographing is effected while a plurality of camera sections are interchanged. Therefore, a color photographing 35 mm camera, a monochromatic photographing 35 mm camera, a color photographing instant camera 1, a color photographing instant camera 2, a color photographing instant camera 3, a monochromatic photographing instant camera, etc. are connected to a camera mount.
During photographing, it is necessary that a power source section and a body determine a quantity of flash fit for the camera section thereof and effect an operation fit for the camera section.
Several parameters are concerned in the determination of the quantity of flash. These parameters include, for example, film speed, the size of the image on the film, photographing angle of view, the type of a filter used during photographing, photographing region, and correction by an exposure correction switch or the like.
In the prior-art eye fundus camera, the instrument has automatically determined the quantity of flash in accordance with pre-programmed conditions (the type of the camera, the set value of film speed SW, the state of the instrument, etc.)
Also, the service life of an ophthalmologic instrument such as an eye fundus camera or a slit lamp is relatively long and therefore, it is often the case that after the sale of products, the machine parts of available camera sections are newly announced. Recently, the requirement for the photographing by electronic still cameras and television cameras has risen and the types of interchangeable camera sections have been on the increase. This has become active in connection with image processing.
In an ophthalmologic instrument such as an eye fundus camera, the optical path changes during observation and during photographing. The optical path during observation terminates at an eyepiece finder and is temporarily changed over to the camera section side only during photographing. That is, the usual optical path terminates at the eyepiece finder.
Therefore, the examiner sets the quantity of light of an observation illumination lamp so that the brightness of the fundus of the examinee's eye observed through the eyepiece finder may be brightness ready to be observed under conditions such as a certain angle of view, a certain filter and a certain diameter of pupil. After once set, the eye fundus camera is designed to automatically control the quantity of observation illumination light in conformity with the various conditions so that the brightness of the fundus of the eye seen through the eyepiece finder may be constant even if an angle of view switching switch, a filter switch, a pupil diameter switching switch, etc. are operated.
Data to be imprinted simultaneously with the image of the fundus of the eye during the photographing of the fundus of the eye is displayed within the eyepiece finder. There are a handwritten data display section for imprinting the examinee's name and information to be preserved as some memorandum and an LED display section available as the clinical chart number, the date of photographing, the number of a group examination, etc. Also, an eye fundus camera having the automatic focusing function has an AF indicator display section for displaying the focused state.
Further, when the image of the fundus of the eye is to be observed with naked eye through the eyepiece finder of the eye fundus camera, the quantity of observation illumination light is set under predetermined conditions as described above, whereby the eye fundus camera controls the quantity of observation illumination light in conformity with said conditions even if said conditions are changed and therefore, the examiner has been able to concentrate on the observation of the image of the fundus of the eye.
However, when the image of the fundus of the eye is to be observed by the use of a television camera, the television camera is connected as a camera section to a camera mount. Thus, the examiner does not observe the image of the fundus of the eye through the eyepiece finder, but observes the image of the fundus of the eye on a CRT screen. However, under the existing circumstances, the image of the fundus of the eye obtained through the eyepiece finder is better in the confirmation of the presence or absence of flare, the resolving power, etc. than that on the CRT screen and therefore, it is observed (as an electronic finder) and photographed (as a television camera device) with the eyepiece finder and the television camera device section changed over.
In the prior art as described above, to decrease the number of the contacts of the camera mount, there is conceivable a method of increasing the number of the steps of a voltage on a signal line, and transmitting a plurality of kinds of information by a signal line. Such a method is not impossible, but is difficult because a great number of steps of a voltage becomes necessary as the kinds of information increase.
Accordingly, it has been impossible to decrease the number of the contacts of the camera mount very much. It has also been impossible to transmit a lot of information even if there is a great number of contacts.
Thus, to obtain a plurality of kinds of information from the camera section, the prior-art method has suffered from a problem.
Also, there are many kinds of camera sections and a film speed setting switch cannot be provided for each camera section and therefore, camera sections of similar kinds set the film speed by one and the same film speed setting switch. This has led to the necessity of re-setting the film speed of the power source section or the body during the interchange of the camera section which serves also as a film speed setting switch. If the user forgets to re-set the film speed, it will become impossible to photograph at proper exposure. Further, an eye fundus camera is used in a state relatively approximate to a dark room and therefore, there has been the problem that when operating a certain film speed setting switch, the user changes another film speed setting switch by mistake. On the other hand, the provision of film speed setting switches corresponding to all camera sections on the power source section or the body results in the presence of too many switches, which has apparently made the instrument difficult to use.
In the prior-art eye fundus camera, the camera section has been directly controlled through the camera mount from the power source section or the body and therefore, it has been necessary to modify the base plate of the power source section or the body or add an interface to the outside in order to take an interface with a new camera section.
Particularly, image processing apparatuses using an eye fundus camera or a slit lamp as an input device differ in interface specification from maker to maker and therefore, it is difficult to modify the base portion of the power source section or the body to thereby cope with numerous camera sections. In the external interface, the camera section is separate from the body and this has led to the problem that the camera section cannot be interchanged by one touch.
Also, the data to be imprinted simultaneously with the image of the fundus of the eye is displayed within the eyepiece finder of the eye fundus camera, as previously described.
These display sections are disposed around the finder and during observation, what one consciously sees can be seen well and thus, it has not posed so great a problem that the display sections are a little too bright. Therefore, the quantity of light in the display sections has been constant when the optical path is on the eyepiece finder side. Only during photographing, the quantity of light has been varied in conformity with the film speed or the size of the image on the film. Nevertheless, during fluorescence photographing, the image of the fundus of the eye is hardly seen, and this has led to the problem that the fundus of the eye becomes difficult to see when the quantity of light for displaying the data is a little too bright.
Further, when the image of the fundus of the eye is to be observed by the use of a television camera, the television camera is connected as a television camera section to the camera mount, but there is a difference between the sensitivity of a naked eye and the sensitivity of the television camera, and this has led to the problem that the quantity of observation illumination light must be re-set each time the optical path is changed over between the eyepiece finder and the television camera section.
That is, in the prior art, the control system of the camera section and the quantity of flash during photographing become necessary as the parameters of each of various camera sections.
Television cameras differ in sensitivity depending on whether the image pickup element used therein is a solid state image pickup element or an image pickup tube or a photomultiplier and further, depending on the area of the image pickup element and one-element or three-element construction and therefore, television camera sections differ in sensitivity depending on the kinds thereof. The sensitivity of the naked eye is irregular from person to person. Thus, there has also been the problem that it is necessary to take the corrected value of the difference in sensitivity between the naked eye irregular in sensitivity and the television camera section.
Further, to photograph the image of the fundus of the eye by a television camera or the like, the image of the fundus of the eye and the data system display sections (the handwritten data display section, the LED display section and the AF indicator display section) are photographed completely at one time. Since the television camera cannot consciously select an image as the naked eye does, the data system display sections are photographed at the same sensitivity. This has led to the problem that particularly during fluorescence photographing, those display sections are too bright and the image field becomes difficult to see.